Light emitting diode module and driving method thereof

Abstract

A light emitting diode module having a plurality of LED strings is provided. The light emitting diode module includes a voltage generating loop, a light tuner, a voltage selector, and a voltage storage and comparison circuit. The voltage generating loop generates a system voltage according to a pulse modulation control signal. The light tuner receives a light tuning signal and turns on or off the LED strings accordingly. The voltage selector selects one of terminal voltages of terminals of the LED strings coupled to the light tuner for generating a selection voltage. The voltage storage and comparison circuit generates an error voltage by comparing the selection voltage and a reference voltage. The voltage storage and comparison circuit stores the error voltage temporarily and provides the temporarily stored error voltage as the pulse modulation control signal.

1 . A light emitting diode (LED) module, having a plurality of LED strings, comprising:
 a voltage generating loop coupled to the LED strings, and the voltage generating loop generating a system voltage according to a pulse modulation control signal;   a light tuner coupled to the LED strings, and the light tuner receiving a light tuning signal and turning on or off the LED strings according to the light tuning signal;   a voltage selector coupled to the light tuner and the LED strings together, and the voltage selector selecting one of terminal voltages of terminals of the LED strings coupled to the light tuner to generate a selection voltage; and   a voltage storage and comparison circuit coupled between the voltage selector and the voltage generating loop, and the voltage storage and selection circuit comparing the selection voltage and a reference voltage to generate an error voltage, wherein the voltage storage and comparison circuit temporarily stores the error voltage and provides the temporarily stored error voltage as the pulse modulation control signal.   
     
     
         2 . The LED module as claimed in  claim 1 , wherein the voltage storage and comparison circuit stores the selection voltage when the light tuner turns off the LED strings according to the light tuning signal. 
     
     
         3 . The LED module as claimed in  claim 1 , wherein the voltage storage and comparison circuit comprises:
 a comparator coupled to the voltage selector to receive the selection voltage, and the comparator comparing the selection voltage and the reference voltage to generate the error voltage; and   a sample and hold circuit coupled between the comparator and the voltage generating loop, and the sample and hold circuit temporarily storing the error voltage according to the light tuning signal to generate the pulse modulation control signal.   
     
     
         4 . The LED module as claimed in  claim 1 , wherein the voltage selector selects the minimum one of the terminal voltages of the terminals of the LED strings coupled to the light tuner to generate the selection voltage. 
     
     
         5 . The LED module as claimed in  claim 1 , wherein, wherein the light tuner comprises:
 a plurality of switches, each of the switches respectively coupled to each of the LED strings, and the switches turned on or off according to the pulse modulation control signal; and   a current driving device coupled the switches, and the current driving device determining whether to provide driving currents to the LED strings correspondingly coupled to the switches according to the switches turned on or off.   
     
     
         6 . The LED module as claimed in  claim 1 , wherein the voltage generating loop comprises:
 a voltage converter receiving an input voltage and a pulse signal, and the voltage converter generating the system voltage by using the input voltage according to the pulse signal; and   a pulse signal modulator coupled to the voltage converter, and the pulse signal modulator generating the pulse signal according to the pulse modulation control signal.   
     
     
         7 . The LED module as claimed in  claim 1 , wherein each of the LED strings comprises:
 at least one LED having a positive terminal coupled to the system voltage and a negative terminal coupled to the light tuner.   
     
     
         8 . An LED module, having a plurality of LED strings, comprising:
 a voltage generating loop coupled to the LED strings, and the voltage generating loop generating a system voltage according to a pulse modulation control signal;   a light tuner coupled to the LED strings, and the light tuner receiving a light tuning signal and turning on or off the LED strings according to the light tuning signal;   a voltage selector coupled to the light tuner and the LED strings together, and the voltage selector selecting one of terminal voltages of terminals of the LED strings coupled to the light tuner to generate a selection voltage; and   a voltage storage and comparison circuit coupled between the voltage selector and the voltage generating loop, wherein the voltage storage and comparison circuit temporarily stores the selection voltage according to the light tuning signal and generates the pulse modulation control signal by comparing the temporarily stored selection voltage and a reference voltage.   
     
     
         9 . The LED module as claimed in  claim 8 , wherein the voltage storage and comparison circuit stores the selection voltage when the light tuner turns off the LED strings according to the light tuning signal. 
     
     
         10 . The LED module as claimed in  claim 8 , wherein the voltage storage and comparison circuit comprises:
 a sample and hold circuit coupled to the voltage selector to receive the selection voltage, and the sample and hold circuit temporarily storing the selection voltage according to the light tuning signal; and   a comparator coupled between the sample and hold circuit and the voltage generating loop, and the comparator comparing the temporarily stored selection voltage and the reference voltage to generate the pulse modulation control signal.   
     
     
         11 . The LED module as claimed in  claim 8 , wherein the voltage selector selects the minimum one of the terminal voltages of the terminals of the LED strings coupled to the light tuner to generate the selection voltage. 
     
     
         12 . The LED module as claimed in  claim 8 , wherein, wherein the light tuner comprises:
 a plurality of switches, each of the switches respectively coupled to each of the LED strings, and the switches turned on or off according to the pulse modulation control signal; and   a current driving device coupled the switches, and the current driving device determining whether to provide driving currents to the LED strings correspondingly coupled to the switches according to the switches turned on or off.   
     
     
         13 . The LED module as claimed in  claim 8 , wherein the voltage generating loop comprises:
 a voltage converter receiving an input voltage and a pulse signal, and the voltage converter generating the system voltage by using the input voltage according to the pulse signal; and   a pulse signal modulator coupled to the voltage converter, and the pulse signal modulator generating the pulse signal according to the pulse modulation control signal.   
     
     
         14 . The LED module as claimed in  claim 8 , wherein each of the LED strings comprises:
 at least one LED having a positive terminal coupled to the system voltage and a negative terminal coupled to the light tuner.   
     
     
         15 . A driving method of an LED module, the LED module comprising a voltage generating loop, a voltage selector, and a voltage storage and comparison circuit, wherein the voltage generating loop generates a system voltage to drive the LED module, the driving method comprising:
 determining whether a light tuning start status of the LED module is activated;   determining that the LED module stays before or after a light tuning status according to a light tuning signal when the light tuning start status is activated;   temporarily storing an error voltage generated by comparing a selection voltage and a reference voltage through the voltage storage and comparison circuit when the light tuning start status is activated, and the LED module stays before the light tuning status, wherein the selection voltage is generated by the voltage selector; and   providing the temporarily stored error voltage to the voltage generating loop through the voltage storage and comparison circuit when the light tuning start status is activated, and the LED module stays after the light tuning status.   
     
     
         16 . The driving method as claimed in  claim 15 , further comprising:
 generating the system voltage according to the temporarily stored error voltage through the voltage generating loop.   
     
     
         17 . The driving method as claimed in  claim 15 , before the step of “determining whether a light tuning start status of the LED module is activated”, the driving method further comprising:
 making the voltage generating loop to generate the stable system voltage. 
 
     
     
         18 . A driving method of an LED module, the LED module comprising a voltage generating loop, a voltage selector, and a voltage storage and comparison circuit, wherein the voltage generating loop generates a system voltage to drive the LED module, the driving method comprising:
 determining whether a light tuning start status of the LED module is activated;   determining whether the LED module stays before or after a light tuning status according to a light tuning signal when the light tuning start status is a start status;   temporarily storing a selection voltage generated by the voltage selector through the voltage storage and comparison circuit when the light tuning start status is activated, and the LED module stays before the light tuning status; and   generating an error voltage by comparing the temporarily stored selection voltage and a reference voltage through the voltage storage and comparison circuit when the light tuning start status is activated, and the LED module stays after the light tuning status.   
     
     
         19 . The driving method as claimed in  claim 18 , further comprising:
 generating the system voltage according to the temporarily stored selection voltage through the voltage generating loop.   
     
     
         20 . The driving method as claimed in  claim 18 , before the step of “determining whether a light tuning start status of the LED module is activated”, the driving method further comprising:
 making the voltage generating loop to generate the stable system voltage.